Portable electronic devices such as mobile phones and netbook computers include antennas for signal transmission and reception to carry out wireless communication functions. However, in view of the growth of wireless charging technology and increasing research efforts in this technology, it is envisaged that many portable electronic devices, including mobile phones and netbook computers, will be re-designed in the near future to embed an energy-receiving coil for wireless charging purposes.
Thus, portable electronic devices with telecommunication functions will require both an antenna for transmitting and receiving RF signals and an energy-receiving coil, which is also called the secondary coil in a wireless battery charging system. With the associated circuitry, this energy-receiving coil is sometimes called the receiver module. To ensure trouble-free operation, and to meet the wireless charging requirements of industry-wide standards and protocols, future portable devices need to have an antenna and an energy-receiving coil that each work independently without adversely affecting the operation of the other.
An antenna inside a mobile phone, for example, could be in the form of a metal plate. If this metal plate is subject to an AC magnetic field (as one would experience in wireless charging), an eddy current can be induced in the antenna, resulting in unwanted induction heating and a reduction in energy efficiency.
Also, to prevent the charging flux from inducing eddy currents in the metallic parts of the portable electronic devices, some form of electromagnetic (EM) shielding may be required for the energy-receiving coil. However, such EM shielding may reduce the strength of the transmitted and received signal in the antenna.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.